When doing manhole rehabilitation or other sewer or other fluid line maintenance, or when otherwise required to bypass flow through a section of pipe or other conduit, and especially large diameter underground piping systems, such as sewer systems, challenges can be encountered when relatively large flow must be maintained during the operation which requires the bypass of the fluid. A standard prior art technique is to utilize a bypass plug and a pump. A bypass plug is inserted into the fluid line upstream of the work area to be bypassed. A flexible tube downstream of this bypass plug is routed up to a surface and out of the pipeline (or otherwise out of the flow pathway which is to be worked upon). Typically, a pump is required to lift the fluid to this lateral position outside of the area to be worked upon. A second conduit will then run downstream to an area safely past the work area and then routed back into the fluid pathway.
This typical prior art solution has numerous drawbacks. Existing bypass plugs have a significantly smaller inside diameter than the pipe in which they are fitted, so that only small flows can be accommodated. Bypass plugs big enough to handle the flow will not fit through the standard twenty-four inch (or even the thirty-six inch) manhole opening. Furthermore, the complexity of setting up and operating the pump is required. Also, the conduits on the surface often produce ancillary problems, such as inhibiting the flow of traffic over streets, when the fluid pathway being worked on is a sewer system (or other fluid lines) located beneath streets.
In some instances it is effective to utilize a pipe plug to completely stop flow. The fluid handling system is merely allowed to back up behind this plug while the work is performed. After the work is completed, the plug is removed and flow recommences. Such a solution is only effective when the work can be done sufficiently rapidly and/or where the flow rates are sufficiently low that backing up of fluids within the pipe does not result in any undesirable effects. This is not the case in many instances.
Accordingly, a need exists for further bypass options, and especially options which can avoid the drawbacks presented in the prior art. In particular, a need exists for bypass systems and methods which can handle large flow rates and fit through a standard manhole opening, and which can avoid routing onto the surface, while still effectively bypassing the work area so that work can be effectively performed. Such systems are desirable that also benefit from being easy to install and remove, and being configured to reliably maintain position and operate effectively, so that work can be safely and efficiently performed on the fluid line while the bypass is in place.